In pots for growing plants of the type described in application Ser. No. 812,344, filed July 1, 1977, a problem exists in the fact that the amount of water in the water reservoir in the pot cannot be determined without disassembly of the inner pot from within the outer pot. In the use of such pots, it is important that at least some water be present in the water reservoir at all times, as otherwise the plant or plants growing in the pot will not be adequately continuously watered. For example, if the directions for supplying water to the reservoir of the pot should call for addition of water once a month, and if the plant and environmental conditions cause use of all of the water in the reservoir before a month has elapsed, there will be a period at the end of each monthly period during which the plant is not watered as contemplated by use of the pots. While experimental data may, within certain bounds of accuracy, indicate that watering for a certain plant at given intervals will be adequate, there are variations in different locations as to relative humidity, and the like, and there are differences in the natures of different plants, so that such experimental data is not sufficiently accurate for proper and adequate use of the pots. This invention is designed to solve this problem in connection with the use of the pots.